The Isolation and Characterization of a New Component of Hemolytic Complement, C′3e

Abstract

Evidence is presented which describes the existence of an eighth fraction of normal guinea pig serum which is essential for the hemolytic action of complement (C′). This component, C′3e, reacts sequentially after C′3b and before C′3f. The intermediate complex, EAb C′1, 4, 2, 3c, 3b, 3e, has a half-life at 30°C of about 75 min. A method for the isolation from whole serum and for the measurement of C′3e reactivity is described. C′3e is depleted from fresh whole serum by antigen-Ab complexes. Purified C′3e appears to be depleted specifically by treatment with EAb C′1, 4, 2, 3c, 3b. Initial studies indicate that C′3e is a macromolecule with a half-life at 56°C of about 41 min. As yet, there are no known co-factors or inhibitors of the hemolytic reactivity of C′3e.